Modern commercial aircraft make extensive use of computer systems to control aircraft behavior, plan and execute flights, and manage a myriad of other aircraft operations. Most current commercial transport aircraft include a flight management computer (FMC) that tracks flight segments or “legs” enroute and can automatically control the aircraft to fly some or all of the segments. A control and display unit (CDU) or a similar device is accessible by the pilot for providing input to and receiving output from the FMC. Accordingly, instructions originating from the FMC are typically implemented automatically when the aircraft passes a pre-identified position or meets another pre-identified threshold condition. For example, the FMC can automatically direct the aircraft to climb, descend, or level off at a particular waypoint, or level off to achieve a constraint altitude.
The aircraft described above typically also include a mode control panel (MCP) at which the pilot can enter flight control instructions for controlling an immediately upcoming portion of the flight. An instruction received from the MCP will be automatically implemented once the pilot authorizes implementation (e.g., by pressing a button) and will then not typically be altered until the pilot enters another instruction at the MCP, takes over control of the aircraft manually, or explicitly directs the control to shift to the FMC.
The MCP and the FMC are typically arranged to interact with each other to resolve potentially conflicting instructions provided by each. Accordingly, in many existing arrangements, the FMC will automatically defer to an instruction authorized at the MCP. One potential drawback with this arrangement is that, when the aircraft is being flown automatically, it may not be clear to the pilot whether the instruction that the aircraft is following is received from the FMC or the MCP. Accordingly, it may take the pilot extra time to determine the source of the instruction, which can cause pilot workload inefficiencies.